Anchor Flanges: Pipeline Axial Force & Thrust Control Solutions
Sunhy manufactures high-performance Anchor Flanges designed to immobilize pipelines and protect critical equipment. Typically embedded in concrete anchor blocks, our flanges effectively transfer axial loads and thermal expansion forces to the foundation. We specialize in Custom Engineered solutions using High Yield Carbon Steel and Stainless Steel to meet specific pipeline pressure and temperature requirements.
Types of Anchor Flanges We Supply
Stainless Steel Flanges
By Design Type
By Standard & Class
Advanced Materials
Anchor Flanges
Why Choose Sunhy for Anchor Flanges?
High-Yield Expertise: We have extensive experience forging high-grade steels (F60, F65, F70) essential for high-pressure pipelines.
Design Capability: We don’t just forge; we can assist with the ASME design calculations to ensure the flange handles the required axial force.
Precision Machining: Accurate beveling ensures a perfect field weld to your pipeline.
Rigorous Testing: Ultrasonic Testing (UT) and Magnetic Particle Inspection (MPI) are standard to guarantee internal structural integrity.
What is an Anchor Flange?
An Anchor Flange is a specialized, axisymmetric piping component designed to restrain pipeline movement caused by thermal expansion or internal pressure changes. Unlike standard flanges, an Anchor Flange has no bolt holes and features two welding hubs. It is welded directly into the pipeline and embedded within a reinforced concrete thrust block. Its primary function is to transfer massive axial thrust loads from the pipe to the surrounding soil, effectively “anchoring” the pipeline to protect downstream equipment like valves and pumps from stress damage.
| Feature | Specification Details |
| Product Name | Anchor Flange, Pipeline Anchor Forging |
| Design Calculation | ASME Section VIII Div. 1 (Custom calculated for specific axial loads) |
| Size Range | 2″ to 60″ (DN50 to DN1500) |
| Pressure Ratings | Equivalent to ASME Class 150, 300, 600, 900, 1500, 2500 |
| Connection Type | Butt Weld (BW) to match pipe wall thickness (Schedule) |
| High Yield Materials | ASTM A694 F42, F52, F60, F65, F70 (Most Common) |
| Carbon Steel | ASTM A105, A350 LF2 |
| Stainless Steel | ASTM A182 F304/304L, F316/316L (For corrosive environments) |
| Coating | Anti-rust oil, Epoxy coating (for buried service) |
Anchor Flange Dimensions & Design
Anchor Flange Dimensions & Calculation Unlike standard B16.5 flanges, Anchor Flanges are rarely “off-the-shelf” items. Their dimensions—specifically the thickness and outer diameter—must be calculated to withstand the specific thrust forces of your pipeline project.
Factors influencing the design include:
Pipe Material Grade (e.g., API 5L X65).
Design Pressure & Temperature.
Concrete Strength (Allowable bearing pressure).
At Sunhyings, our engineering team performs the necessary calculations to optimize the flange weight while ensuring safety. > Need a drawing? Send us your pipeline data, and we will provide a preliminary design and quote.
Applications
Pipeline Landfalls & River Crossings: Securing the pipe where it transitions from underground to above-ground.
Compressor & Pumping Stations: Protecting sensitive rotating equipment from pipe thermal growth.
Subsea Pipelines: Managing end-expansion in offshore lines.
Riser Connections: At the base of risers on platforms.
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FAQ
Do Anchor Flanges Have Bolt Holes?
Absolutely not. The absence of bolt holes is the most distinct physical characteristic that differentiates an Anchor Flange from standard flanges (such as Weld Neck or Blind Flanges). Anchor Flanges are designed specifically to be embedded in concrete to restrain movement, not to be bolted to other piping components. If a flange has bolt holes, it is not an Anchor Flange.
Can typical flanges be used instead of Anchor Flanges for buried applications?
No, they cannot. Standard flanges are primarily designed to contain internal pressure and connect pipe sections via bolts. They lack the specific structural geometry required to transfer massive axial thrust loads into a concrete thrust block. Using a standard flange for anchoring would likely lead to stress concentrations that could cut into the concrete or cause the flange to fail, compromising the pipeline’s integrity.
How are Anchor Flanges maintained?
They are designed to be maintenance-free. Once an Anchor Flange is welded into the pipeline and buried within a reinforced concrete thrust block, it is no longer accessible. Therefore, quality control during the initial installation—specifically regarding welding, coating, and concrete pouring—is critical, as these components must last for the entire service life of the pipeline (typically 30-50 years) without further intervention.
What is the difference between ASTM A105 and A694 F60 materials?
The primary difference is Yield Strength.
ASTM A105 is a standard carbon steel forging with a minimum yield strength of approximately 36,000 psi (36 ksi). It is suitable for low-to-medium pressure general piping.
ASTM A694 F60 is a High-Yield Carbon Steel with a minimum yield strength of 60,000 psi (60 ksi). It is essential for high-pressure oil and gas transmission lines to match the strength of high-grade pipes (like API 5L X60). Using A105 on a high-strength pipeline creates a weak point that could yield during pressure testing.
Why does my Anchor Flange drawing specify a "Taper Bore"?
This is required to manage Wall Thickness Mismatch. Anchor Flanges are heavy forgings with a body thickness significantly greater than the pipe they connect to. A “Taper Bore” (usually with a 1:4 slope) is machined into the flange end to create a smooth, gradual transition from the thick flange to the thinner pipe wall. This reduces stress concentration at the weld joint and ensures a smooth flow profile for manufacturing and inspection (pigging).